Dialkylphosphatidylcholine and egg yolk lecithin for emulsification of various triglycerides.

Synthesized saturated phosphatidylcholine (PC) and egg yolk lecithin (EYL) were investigated to explore their influence on particle sizes in emulsions when dispersing various triglycerides (TG). One of four different kinds of synthesized saturated PC (DLPC, DMPC, DPPC and DSPC) or three different kinds of EYL (purified EYL (PEL) and hydrogenated purified EYL with two different iodine values (IV), R-20 and R-5), 2.5% (w/w) glycerol solution and one of four kinds of TG (tricaprylin, tricaprin, trilaurin and trimyristin) were sonicated five times for 1 min with intervals of 0.5 min. When using four kinds of synthesized saturated PCs as emulsifiers, the carbon numbers of each PC had a strong correlation with the mean diameters of the emulsion when analyzed with each of the four kinds of TG used in the study (regression function ranged from 0.811 to 0.915). The carbon numbers of the TG had less correlation with the mean diameters than the PC in simple regression analysis (regression function ranged from 0.236 to 0.875). Multiple regression analysis using the carbon numbers both of the PC and TG as independent variables was remarkably significant in the regression function (2.0 x 10(-14)) and all regression coefficients (2.7 x 10(-13), 5.8 x 10(-7) and 1.9 x 10(-9) for PC, TG and intercept, respectively). Among the regression coefficients, the contribution of the carbon number of the PC was the most significant. These results indicated that a multiple regression function should be useful to estimate the mean diameters of emulsion droplets in any combinations of PC and TG used in this study. In the experiments using three kinds of EYL, the mean diameters also tended to increase according to the order of PEL, R-20 and R-5, which corresponds to the order of degrees of saturation (IV = 75, 20 and 2, respectively). The experimental values for EYL were compared with the estimated values calculated by the multiple regression function derived from synthesized PC data using the arithmetic carbon number, based on the components of each EYL. The estimated mean diameters were at comparable levels to the corresponding experimental mean diameters in the most saturated hydrogenated lecithin (R-5), while those were larger than the experimental mean diameters in two less saturated kinds of lecithin (R-20 and purified EYL). These findings gave useful information on the mean diameters of emulsion droplets when designing an emulsion formulation using a particular combination of a phospholipid and triglyceride.